A demonstration unit for the Solar-Assisted Large-Scale Cleaning System (SALSCS), with a solar collector 43 × 60 m2 in horizontal dimensions and a tower 60 m in height, was built in Xi’an, China, to study its effectiveness in terms of urban air pollution remediation. To simulate an urban-scale SALSCS with dimensions ranging 10–120 m that was proposed for installation on urban blocks, we first performed experimental measurements on the demonstration unit and used the experimental data to validate a numerical model that we developed. This paper presents the field measurements conducted during three days in Jan. 2017 in Xi’an. The experimental and numerical results of the system flow rate and temperature showed good agreement for six of the eight measurement cases, with average discrepancies of 1.63 m3 s–1 for the flow rate and 0.78°C for the temperature. Larger discrepancies for the other two cases were observed, and the reasons were analyzed. During the measurements, the filtration efficiency of the filter media installed in the north section of the system with regard to PM2.5 was evaluated to be 73.5%. The validated numerical model was applied to study the performance characteristics of the urban-scale SALSCS, and these results will be presented in Part II.